Transmission efficiency of an optical transmission path using optical fiber is greatly affected by connection loss at an optically connected part, such as between plural optical fibers or between an optical fiber and another optical part such as optical semiconductor device. As a cause of the connection loss at these connecting parts, one concerning aligning of optical fibers, such as mismatched axes, an inclined axis, or a gap between the end surface of optical fibers may be mentioned, and one concerning an end surface of an optical fiber such as an inclined surface, surface roughness, or surface waving can be mentioned.
To eliminate these causes efficiently, there is a method in which a connecting device is made to have a complicated structure and high precision, and a method in which highly precise grinding is performed on an end surface of an optical fiber. However, there were problems of increased cost when connecting the optical fiber.
Furthermore, an optical connecting structure in which an adhesive connecting member is attached on a tip of an optical fiber and the optical fiber is connected to another optical fiber or an optical part via the adhesive connecting member to enable reduction of connection loss, which is a problem in optical communication, has been suggested (see Japanese Unexamined Patent Application Publication No. 2006-221031).
FIG. 8 is a side view showing a concept of an optical connecting structure in which a conventional adhesive connecting member is used. Reference numerals 10a and 10b correspond to optical fibers, and reference numeral 21 corresponds to a conventional sheet-shaped adhesive connecting member. In FIG. 8, the sheet-shaped adhesive connecting member 21 intervenes between the connecting end surfaces of the optical fibers 10a and 10b in a condition of adhering to both. The two optical fibers 10a and 10b face each other via the sheet-shaped adhesive connecting member 21, and they thereby optically connect the optical fibers.
However, in the method in which the above-mentioned conventional adhesive connecting member is used, it is difficult to reattempt connection if aligning and adhesion have failed once. Therefore, further improvement has been desired to facilitate handling. Furthermore, in this method, since it is necessary to cut the adhesive connecting member to a required size to attach onto the tip of the optical fiber while taking into consideration dust in the air, extremely careful handling is required, and in conditions outside a clean room, such as in conditions in the field, it is difficult to perform the connection of the optical fiber.